This invention relates generally to devices and methods for screening arrays of coatings and, more specifically, to devices and methods for the comparative evaluation of the abrasion resistance of coating samples comprising a coating array.
Due to the complex nature of coatings, such as protective/decorative coatings, barrier coatings, adhesive/release coatings, optic transparent coatings, anticorrosive coatings, electric conductive coatings, and scratch resistant coatings, it is difficult to predict coating performance using basic scientific principles. As a result, the formulation of an effective coating commonly requires extensive experimentation. To accelerate the coating development process, automation of the production of coating samples, miniaturization of these coating samples, and high throughput screening of important coating properties are highly desirable.
An important consideration in the development of coatings, especially those used for the protection of plastic substrates, is abrasion resistance. A typical method for measuring abrasion resistance is the measurement of haze. In this method, a relatively large area of coating, about 1 cm2, is measured, using optical interrogation techniques, to quantify transmitted and diffused, or scattered, light. Haze is the ratio of scattered light to transmitted light. This method, however, has several important shortcomings that limit its applicability to the high throughput screening of combinatorial libraries, including: 1) the requirement of having large coating areas for measurement; 2) the inability to obtain reliable haze measurements of less than 1%; 3) the inability to measure abrasion resistance in optically transparent coatings on a substrate; 4) the inability to rapidly measure multiple samples; and 5) difficulty in measurement automation.
Therefore, there is a need for automated, high throughput devices and methods for screening arrays of coatings for abrasion resistance. Further, there is a need for devices and methods for measuring abrasion resistance that are sensitive and that require only small coating samples for accurate measurement.
Thus, the present invention provides devices and methods for the high throughput screening of the abrasion resistance of coatings.
A device of one embodiment for the high throughput screening of the abrasion resistance of coatings includes a plurality of transducers, each of the plurality of transducers having at least one external surface, and a plurality of coatings, each of the plurality of coatings deposited onto the external surface(s) of one of the plurality of transducers. Further, the device includes a plurality of oscillation sources, coupled to the plurality of transducers, operable for generating and applying an oscillation potential to each of the plurality of transducers. Finally, the device includes a plurality of oscillation detectors, coupled to the plurality of transducers, operable for measuring the oscillation frequency and variation in oscillation frequency in each of the plurality of transducers. Each of the plurality of coatings is exposed to an abrasive material causing a change in mass in each of the plurality of coatings. This change in mass results in a variation in oscillation frequency in each of the plurality of transducers.
A method of one embodiment for the high throughput screening of the abrasion resistance of coatings includes providing a plurality of transducers, each of the plurality of transducers having at least one external surface, and depositing a plurality of coatings onto the external surface(s) of the plurality of transducers, each of the plurality of coatings deposited onto the external surface(s) of one of the plurality of transducers. Further, the method includes generating and applying an oscillation potential to each of the plurality of transducers. The method also includes exposing each of the plurality of coatings to an abrasive material, the abrasive material causing a change in mass in each of the plurality of coatings. Finally, the method includes detecting and measuring the oscillation parameters and variation in oscillation parameters in each of the plurality of transducers, wherein a first oscillation parameter corresponds to an unabraded coating and a second oscillation parameter corresponds to an abraded coating, the variation in oscillation parameter corresponding to the change in mass and/or viscoelastic property in each of the plurality of coatings.